JEE Challenger
More from Coordination Compounds
ChemMedAdv 2023 • Paper 1

Matching Electronic Configurations with Metal Complex Ions

Match the electronic configurations in List-I with appropriate metal complex ions in List-II and choose the correct option. [Atomic Number: Fe=26,Mn=25,Co=27\text{Fe} = 26, \text{Mn} = 25, \text{Co} = 27]

List-IList-II(P) t2g6eg0(1) [Fe(H2O)6]2+(Q) t2g3eg2(2) [Mn(H2O)6]2+(R) e2t23(3) [Co(NH3)6]3+(S) t2g4eg2(4) [FeCl4]−(5) [CoCl4]2−\begin{array}{ll} \text{List-I} & \text{List-II} \\[5pt] (P)\ t_{2g}^6 e_g^0 & (1)\ [\text{Fe}(\text{H}_2\text{O})_6]^{2+} \\[4pt] (Q)\ t_{2g}^3 e_g^2 & (2)\ [\text{Mn}(\text{H}_2\text{O})_6]^{2+} \\[4pt] (R)\ e^2 t_2^3 & (3)\ [\text{Co}(\text{NH}_3)_6]^{3+} \\[4pt] (S)\ t_{2g}^4 e_g^2 & (4)\ [\text{FeCl}_4]^- \\[4pt] & (5)\ [\text{CoCl}_4]^{2-} \end{array}

Options

A

P→1;Q→4;R→2;S→3P \rightarrow 1; Q \rightarrow 4; R \rightarrow 2; S \rightarrow 3

B

P→1;Q→2;R→4;S→5P \rightarrow 1; Q \rightarrow 2; R \rightarrow 4; S \rightarrow 5

C

P→3;Q→2;R→5;S→1P \rightarrow 3; Q \rightarrow 2; R \rightarrow 5; S \rightarrow 1

D

P→3;Q→2;R→4;S→1P \rightarrow 3; Q \rightarrow 2; R \rightarrow 4; S \rightarrow 1

Correct

Topics & Concepts

Coordination CompoundsCoordination CompoundsCrystal Field Theory

Step-by-Step Solution

To determine the correct matching between the electronic configurations in List-I and the metal complex ions in List-II, we analyze each complex ion based on Crystal Field Theory (CFT):

  1. Complex (1): [Fe(H2O)6]2+[\text{Fe}(\text{H}_2\text{O})_6]^{2+}

    • Central Metal Ion: Fe2+\text{Fe}^{2+} (Atomic number of Fe=26\text{Fe} = 26)
    • Valence Shell Configuration: 3d63d^6
    • Geometry: Octahedral
    • Ligand: H2O\text{H}_2\text{O} is a weak field ligand, resulting in a high-spin complex.
    • CFT Configuration: Electrons fill the t2gt_{2g} and ege_g orbitals according to Hund's rule for high spin: t2g4eg2t_{2g}^4 e_g^2
    • Matches: (S)→1(\text{S}) \rightarrow 1

  2. Complex (2): [Mn(H2O)6]2+[\text{Mn}(\text{H}_2\text{O})_6]^{2+}

    • Central Metal Ion: Mn2+\text{Mn}^{2+} (Atomic number of Mn=25\text{Mn} = 25)
    • Valence Shell Configuration: 3d53d^5
    • Geometry: Octahedral
    • Ligand: H2O\text{H}_2\text{O} is a weak field ligand, resulting in a high-spin complex.
    • CFT Configuration: t2g3eg2t_{2g}^3 e_g^2
    • Matches: (Q)→2(\text{Q}) \rightarrow 2

  3. Complex (3): [Co(NH3)6]3+[\text{Co}(\text{NH}_3)_6]^{3+}

    • Central Metal Ion: Co3+\text{Co}^{3+} (Atomic number of Co=27\text{Co} = 27)
    • Valence Shell Configuration: 3d63d^6
    • Geometry: Octahedral
    • Ligand: NH3\text{NH}_3 acts as a strong field ligand with Co3+\text{Co}^{3+}, causing pairing of electrons to form a low-spin complex.
    • CFT Configuration: t2g6eg0t_{2g}^6 e_g^0
    • Matches: (P)→3(\text{P}) \rightarrow 3

  4. Complex (4): [FeCl4]−[\text{FeCl}_4]^-

    • Central Metal Ion: Fe3+\text{Fe}^{3+} (Atomic number of Fe=26\text{Fe} = 26)
    • Valence Shell Configuration: 3d53d^5
    • Geometry: Tetrahedral (Coordination number = 4)
    • CFT Splitting: In a tetrahedral field, the ee orbitals are lower in energy than the t2t_2 orbitals. Tetrahedral complexes are almost universally high-spin.
    • CFT Configuration: e2t23e^2 t_2^3
    • Matches: (R)→4(\text{R}) \rightarrow 4

  5. Complex (5): [CoCl4]2−[\text{CoCl}_4]^{2-}

    • Central Metal Ion: Co2+\text{Co}^{2+}
    • Valence Shell Configuration: 3d73d^7
    • Geometry: Tetrahedral
    • CFT Configuration: e4t23e^4 t_2^3

Comparing the matches obtained:

  • (P)→3(\text{P}) \rightarrow 3
  • (Q)→2(\text{Q}) \rightarrow 2
  • (R)→4(\text{R}) \rightarrow 4
  • (S)→1(\text{S}) \rightarrow 1

This set of matches corresponds to Option (D).

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